The following description of the background of the invention is provided simply as an aid in understanding the invention and is not admitted to describe or constitute prior art to the invention.
Vegetable oils have been used as alternative fuels and feedstocks for the production of biodiesels. Generally the oils used are extracted from plants grown in large quantity in a particular region. Therefore, soybean oil is of interest as a source of biodiesel in the United States, whereas rapeseed oil is of interest in European countries; and countries having tropical climates utilize coconut oil or palm oil (Knothe et al., published on-line at the URL www.biodiesel.org/resources/reportsdatabase/reports/gen/19961201_gen-162.pdf).
A composition of triglycerides simulating the oil from VS-320, a mutant Cuphea viscossima, is disclosed by Geller et al. (Transactions of the American Society of Agricultural Engineers 42:859-862, 1999). The “simulated analogue of VS-320 oil” disclosed in Geller has a triglyceride composition of 4.2% C6:0; 40.20% C8:0; 36.90% C10:0; 4.80% C12:0; 6.80% C14:0; 3.33% C16:0; 0.00% C18:0; 1.37% C18:1; 2.05% C18:2; and 0.00% C18:3 (see Table 1). Geller et al., (1999) concluded that “[t]his model suggests that an increase in the C8:0 content of vegetable oils along with a subsequent reduction in medium- and long-chain triglycerides may result in a more efficient, better performing alternative diesel fuel.”
Stournas, et al., (JACOS, 1995, 72:433-437) discloses characteristics of various oils as fuels and states “[g]ven the ±3° C. repeatability of pour point determinations, most of the added components did not appear to affect the −12° C. pour point of the base fuel to a significant degree. The major exceptions are the saturated fatty alcohols with C12 and longer alkyl chains, which increase the pour point substantially; minor negative effects were also observed with some of the longer-chain esters. It is worth noticing that the presence of the double bond in all oleate derivatives sharply improves their cold flow behavior in comparison to the corresponding stearates” and “[w]hen both ignition quality and cold flow behavior are taken into account, the tertiary dimethylamines are the best performers; however, the tertiary amides also appear to be interesting prospects, in that their preparation from the glycerides of natural vegetable oils may be much simpler than that of the amines, as some recent studies have shown.”
Mittelbach (Bioresource Technology, 1996, 56:7-11) discusses specifications and quality control of diesel fuel derived from vegetable oils and states “[o]ne parameter which has not yet been included in the Austrian standards for RME, but might be necessary when defining general standards for fatty acid methyl esters is the iodine number, which describes the content of unsaturated fatty acids and is only dependent on the origin of the vegetable oil. In Germany a value of 115 is defined, which corresponds to rapeseed oil, but would exclude different kinds of oils, like sunflower oil and soybean oil. A limitation of unsaturated fatty acids may be necessary, due to the fact that heating higher unsaturated fatty acids results in polymerization of glycerides. This can lead to the formulation of deposits or to deterioration of the lubricating oil. This effect increases with the number of double bonds in the fatty acid chain. Therefore, it seems better to limit the content of higher unsaturated fatty acids like linolenic acid, than to limit the degree of unsaturation with the iodine number.”
Graboski (Prog. Energy Combustion Sci., 1998, 24:125-164) discusses “the statues of fat and oil derived diesel fuels with respect to fuel properties, engine performance, and emissions” and states “[r]educing chain length and/or increasing chain branching would improve the cold flow properties of the fuel. Chain length and degree of branching might be altered through both plant breeding or genetic engineering approaches, as well as through chemical processing of the biodiesel to cleave certain double bonds or to form branched isomers. Very little practical research has been done in the chemical processing area. The cold flow properties of biodiesel fuels are clearly an area in need of considerable research.”
Goodrum et al., (Bioresource Technology, 1996, 56:55-60) discusses “physical properties of low molecular weight triglycerides for the development of bio-diesel fuel models” and states “[o]ils which contain significant fractions of low molecular weight triglycerides might be suitable for direct use as fuel extenders. In fact, feedstock from Cuphea species (Graham, 1989), contains oils predominantly composed of these triglycerides (particularly tricaprylin and tricaprin). Modern DNA transfer technologies might also afford the transfer of genes that control the synthesis of low molecular weight triglycerides from species such as Cuphea into other more well-established oilseed crops. Oil composition could then be genetically modified for the optimal desired biodiesel properties.”
Knothe (Fuel Processing Technology, 2005, 86:1059-1070) states “[s]aturated fatty compounds have significantly higher melting points than unsaturated fatty compounds (Table 1) and in a mixture they crystallize at higher temperature than the unsaturates. Thus biodiesel fuels derived from fats or oils with significant amounts of saturated fatty compounds will display higher cloud points and pour points.”
Kinney et al., (Fuel Processing Technology, 2005, 86:1137-1147) discusses issues regarding modification of soybean oil for enhanced performance biodiesel blends. This article references the blends disclosed in Geller et al., 1999 and states “since the melting point of biodiesel derived from these short-chain fatty acids is fairly high, additional winterization steps would be required to improve cold flow properties.” Kinney et al. also states “[a]lterations in the fatty acid profile that increase the saturated fatty acid content will augment oxidative stability but worsen cold flow . . . the presence of double bonds in fatty acids will lower the cetane number; hence, strategies to shift the fatty pool of a vegetable oil towards saturated moieties will improve ignition quality of the derived biodiesel, but as with oxidative stability may compromise cold flow properties.”
U.S. Pat. No. 4,364,743 (“the '743 patent”) discloses “a synthetic fuel of fatty acid esters [that] provides a novel source of energy when burned alone or in combination with other known fuels,” and that “[e]sters are preferably prepared by a transesterification reaction using various oils such as soya oil, palm oil, safflower oil, peanut oil, corn oil, cottonseed oil, linseed oil, oiticica oil, tung oil, coconut oil, castor oil, perilla oil, rapeseed oil, sunflower oil, lard, tallow, fish oils, blubber, lipids from marine and land animals and lipids from vegetable sources.”
U.S. Pat. No. 5,389,113 (“the '113 patent”) discloses “mixtures containing a) 58 to 95% by weight of at least one ester with an iodine value of 50 to 150 derived from fatty acids containing 12 to 22 carbon atoms and lower aliphatic alcohols containing 1 to 4 carbon atoms, b) 4 to 40% by weight of at least one ester of fatty acids containing 6 to 14 carbon atoms and lower aliphatic alcohols containing 1 to 4 carbon atoms and c) 0.1 to 2% by weight of at least one polymeric ester.”
US Patent Application Publication No. 2006026963 discloses “nucleic acid constructs and methods for producing altered seed oil compositions” and states “a method to enhance oleic acid content and reduce saturated fatty acid content in a plant seed comprising i) shortening the length of a first heterologous FAD2 sequence until the amount of FAD2 gene suppression from a plant transformed with the first heterologous FAD2 sequence is at least partially reduced relative to the amount of FAD2 gene suppression in a plant cell comprising a similar genetic background and a second heterologous FAD2 sequence, wherein the second heterologous FAD2 sequence consists of more endogenous FAD2 sequence than the first heterologous FAD2 sequence; ii) expressing a heterologous FATB sequence capable of at least partially reducing FATB gene expression in a plant cell relative to the suppression of FATB in a plant cell with a similar genetic background but without the heterologous FATB sequence; iii) growing a plant comprising a genome with the first heterologous FAD2 sequence and the heterologous FATB sequence; and iv) cultivating a plant that produces seed with a reduced saturated fatty acid content relative to seed from a plant having a similar genetic background but lacking the first heterologous FAD2 sequence and the heterologous FATB sequence.”